JP2002168573A - Method for melting metal and metal block for use in that method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce fuel consumption significantly by improving the method for filling the preheating column of a metal melting/holding furnace with metal blocks. SOLUTION: Metal blocks (20) are thrown into a preheating column (2) and then melted and molten metal (5) is fed to a next process. In such a method for melting metal in a metal melting/holding furnace (1), pyramidal or truncated pyramidal metal blocks (20) are stacked fully in the preheating column (2) and the fully stacked metal blocks (S) are melted sequentially from the bottom part while passing hot air upward through the gaps (21) between the metal blocks (20).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing the oxidation of metal lumps in a preheating tower by improving the filling state of the metal lumps charged into the preheating tower of a metal melting and holding furnace, and reducing the heat radiation inside the furnace. The present invention relates to a novel method for dissolving a metal, which can prevent and improve the thermal efficiency, and can further enhance the dissolution rate of the metal lump, and a metal lump used in the method.

[0002]

2. Description of the Related Art As shown in FIG. 5, a conventional metal melting and holding furnace (B) includes an ingot and a metal scrap (4) in a preheating tower (32).
0), and the melting burner (3) provided at the bottom of the preheating tower (32).
In 6), the metal scrap (40) is sequentially melted from the bottom thereof, sent to the molten metal holding chamber (33), and is heated by the melting burner (36) installed at the bottom of the well adjacent to the molten metal holding chamber (33). 34) from molten metal
(35) is pumped out and the molten metal (35) is sequentially supplied to a die casting machine (not shown). After the flame (36a) of the melting burner (36) melts the metal chips (40) at the bottom of the preheating tower (32) sequentially, it becomes high-temperature exhaust gas and rises rapidly through the space between the metal chips (40), It was released to the atmosphere from the raw material inlet (32a) of the preheating tower (32).

As the metal scrap (40) is mainly made of scrap shredder scrap, a rod-shaped object, a disk-shaped object,
Stars and other shapes are included. Therefore, the metal scraps (40) charged into the preheating tower (32) are entangled with each other and filled, and gaps of various sizes are formed between the metal scraps (40), and the preheating tower (32) The packing density of the metal scraps (40) filled in is low. As a result, the melting burner
The flue gas of (36) passes through the preheating tower (32) in a short time without any resistance and is released to the atmosphere. The temperature of the flue gas discharged to the atmosphere is high, and the metal waste (40) is released to the atmosphere without being sufficiently preheated.Therefore, the thermal efficiency of the entire metal melting and holding furnace (B) is greatly reduced, and a large heat loss is caused. Had to be forced.

Further, the combustion exhaust gas is supplied to the preheating tower (3
2) Ascends in a short time and is released to the atmosphere with incomplete combustion before complete combustion, so the fuel consumption increases accordingly. Therefore, the amount of carbon dioxide emission increases in proportion to the fuel consumption, thereby doubling the environmental pollution. In addition, when the metal scrap (40) is used as the input material, there is a serious problem in that the dissolving speed is low and the working efficiency is improved due to the low packing density of the preheating tower (32).

[0005] When metal scrap (40) is used, a preheating tower is used.
In (32), the metal debris (40) is entangled with each other and forms an arch (or bridge) on the way and does not fall, and the metal debris (40) below the arch is melted to form a cavity, and this arch is formed. Eventually, it collapsed and hit the furnace bottom of the melting chamber (34), damaging the furnace bottom, and the sharp tip of the metal scrap (40) was
There is also a problem that the inner wall is damaged by contacting the inner wall while passing through.

[0006]

The problem to be solved by the present invention is as follows.
An object of the present invention is to solve the above problems at once by improving a method of filling a metal lump into a preheating tower of a metal melting and holding furnace and a shape of a metal lump used in the method.

[0007]

The first aspect of the present invention relates to a method of the present invention, comprising the steps of: "a preheating tower (2) for preheating a charged metal mass (20); (20) is melted, and the molten metal (5) is supplied to the next step in a metal melting and holding furnace (1). (2) Filling and laminating inside, the laminated filling (S) is melted sequentially from the bottom, and hot air rises through the gap (21) of the metal lump (20). '' And

According to this method, since the packing density in the preheating tower (2) is increased, the gap (21) generated between the metal blocks (20) is very small, and the metal block (20) at the bottom is melted. The high-temperature exhaust gas slowly rises in the narrow gap (21) over time, during which time the metal mass (20) is sufficiently heated to be released into the atmosphere as a low-temperature exhaust gas. As a result, fuel consumption is greatly reduced, thermal efficiency is greatly improved, and carbon dioxide emissions are correspondingly significantly reduced. Further, the high-temperature exhaust gas rises in the preheating tower (2) over time, and is completely burned. Most of the carbon dioxide is CO2, CO, SOx, NOx, etc. are reduced, and the exhaust gas is discharged as a clean exhaust gas.

When the shape of the metal lump (20) is a polygonal pyramid or a truncated polygonal pyramid, the shape is simple, so that the metal lump (20) does not become entangled with each other in the preheating tower (2) to form an arch. The dissolving operation can be smoothly performed by descending smoothly in the preheating tower (2), and the dissolving speed itself can be increased because preferential melting is performed from thin corners and ridges of the meat. If the pyramid or the truncated pyramid is rounded, the inner wall of the preheating tower (2) will not be damaged while passing through the preheating tower (2).

[0010] Claim 2 is an example of a metal lump (20) used in the metal melting method according to claim 1, characterized in that its shape is a truncated quadrangular pyramid. Thus, when the shape of the metal lump (20) used in the melting method of the present invention is a truncated pyramid and the metal lump (20) is charged into the preheating tower (2), the metal lump (20) The gap (21) between them becomes very narrow, so that the high-temperature exhaust gas becomes difficult to pass through between the metal lumps (20) and is easily melted, so that the action as claimed in claim 1 is obtained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. The metal melting and holding furnace (1) of the present invention is a reflection type furnace, and a preheating tower for preheating the charged metal mass (20).
(2), provided at the bottom of the preheating tower (2), a melting burner (6)
Is installed, the molten metal (5) melted in the melting chamber (10) flows in, and the molten metal holding chamber (3) is maintained at a predetermined temperature, and the molten metal holding chamber (3) And a well (4) for drawing a molten metal (5).

The preheating tower (2) has a rectangular cylindrical shape and the lower part is a melting chamber.
(10), and a melting burner is provided on the side wall of the melting chamber (10).
(6) is installed. The bottom of the melting chamber (10) is the molten metal holding chamber
It is inclined toward (3), and the molten metal (5) melted in the melting chamber (10) flows smoothly into the molten metal holding chamber (3). At the top of the preheating tower (2), a floodlight (9a) and a light receiver
A level sensing device (9) constituted by (9b) is provided.

The molten metal holding chamber (3) following the melting chamber (10) is a rectangular space in which a temperature holding burner (7) is installed on the ceiling, and the molten metal held in the molten metal holding chamber (3). A flame is radiated from above on (5) to maintain the molten metal (5) in the molten metal holding chamber (3) at a predetermined temperature. The temperature of the molten metal (5) in the molten metal holding chamber (3) is constantly sensed by a thermometer (not shown).

The well (4) adjacent to the molten metal holding chamber (3) is a molten metal.
In the part for drawing out (5), the upper surface is open so that the molten metal (5) can be drawn out and communicates with the molten metal holding chamber (3) through the communication passage (11), Always, molten metal holding room (3)
The molten metal (5) maintained at a predetermined temperature is supplied to the well (4).

Outside the metal melting and holding furnace (1), an input packet from the material storage site to the material input port (2a) of the preheating tower (2).
(8) is installed, and the metal lump (20) is charged into the preheating tower (2) from the material charging port (2a) by the charging bucket (8) as needed.

The shape of the metal block (20) used in the method of the present invention is a polygonal pyramid or a truncated polygonal pyramid. In this embodiment, as shown in FIGS. It is a stand. Of course, the shape of the metal lump (20) is not limited to a truncated pyramid, and may be a triangular pyramid, a quadrangular pyramid, or a truncated triangular pyramid. This metal lump
The reason for making the shape of (20) a polygonal pyramid or a truncated polygonal pyramid is that the metal lump is put into the preheating tower (2) from the material charging port (2a) by the charging bucket (8).
This is because when (20) is charged, the preheating tower (2) can be uniformly and densely packed. Although the material of the metal block (20) is not particularly limited, aluminum, zinc, copper, or the like is generally used.

Next, a melting method using the metal lump (20) will be described. The metal lump (20), which is a molten material, is charged into the charging packet (8) from the material charging port (2a) into the preheating tower (2). Is filled in the preheating tower (2) in a suitable state. At this time, the gap (21) between the metal blocks (20) is narrow, and the passage resistance of the high-temperature exhaust gas becomes very large. Further, since the shape of the metal lump (20) is a polygonal pyramid or a truncated polygonal pyramid (here, a truncated pyramid) having rounded corners and ridges as described above, the metal lump is formed on the inner wall of the preheating tower (2). mass
Even if (20) comes into contact, the inner wall of the preheating tower (2) is hardly damaged. The input amount is sensed by a level sensing device (9) above the preheating tower (2).

[0018] The stacked packing (S) of the metal lump (20) in the preheating tower (2)
Is sequentially melted from the bottom of the laminated packing body (S) by the flame of the melting burner (6), and flows into the molten metal holding chamber (3) sequentially through the inclined floor surface. This metal lump (20) has a thinner wall at the corners and ridges than the central part, so it is easy to heat up, and it is easy to melt from this part, and it melts smoothly and quickly from the bottom of the laminated packing material (S) sequentially. To go.

The high-temperature flue gas in which the metal lump (20) at the bottom of the stacked packing (S) is dissolved forms a narrow gap (21) between the metal lump (20).
Through the preheating tower (2), slowly ascending over time to sufficiently preheat the metal lump (20), and the combustion exhaust gas itself is completely burned during this time. CO, NOx, SOx, etc. contained in the flame erupted from the melting burner (6)
(20) completely burns while passing through the gap (21) and the preheating tower
Exhaust gas discharged from the raw material inlet (2a) of (2) is sufficiently preheated to the metal lump (20) to a low temperature (a temperature drop of about 200 ° C. was observed as compared with the conventional case), and almost. With carbon dioxide alone, NOx and SOx are also very clean. As a result, the fuel consumption is greatly reduced, about 16-3
A fuel reduction rate of 0% can be achieved.

Further, in such a combustion state, the inside of the furnace is kept in a reduced state, and the combustion exhaust gas slowly rises in the preheating tower (2) to maintain the inside of the preheating tower (2) at a positive pressure. For,
Outside air does not enter the furnace through the preheating tower (2), and oxidation of the metal block (20) preheated in the preheating tower (2) is also prevented.

Example 1 A melting experiment of a metal lump according to the present invention with a conventional metal scrap was conducted using a 1.2-ton Homel furnace having a melting amount of 200 kg per unit time as a metal melting furnace. . The amount of test material used was 502 kg. The total calories of the fuel required for dissolving the metal lump according to the present invention,
It is 1,513,944 kcal / ton, and in the case of conventional metal scrap, it is 1,798,333 kcal / ton, and a 15.8% fuel reduction was realized.

(Example 2) A melting experiment of a metal lump according to the present invention and a conventional metal scrap was conducted using a 1.5-ton homel furnace having a melting amount of 350 kg per unit time as a metal melting furnace. . The amount of test material used was 450 kg. The total calories of the fuel required to melt the metal lump according to the present invention is 6
27,000 l / ton, and 8 for conventional metal scrap.
It was 50,000 l / ton, and a fuel reduction of 26.2% was realized.

(Example 3) A melting experiment of a metal lump according to the present invention and a conventional metal scrap was performed using a 2.5 ton homer furnace having a melting amount of 500 kg per unit time as a metal melting furnace. . The amount of test material used was 1,000 kg.
The amount of fuel gas used for melting the metal lump according to the present invention is:
25.86 m ³ , 85.0 m for conventional metal scrap
0 m ³ , and 30.4% fuel reduction was achieved. As seen from the examples, the larger the furnace, the higher the energy saving effect tends to be.

[0024]

According to the method of the present invention, metal pyramids or truncated pyramid metal blocks are stacked and filled in the preheating tower, so that the packing density of the metal blocks in the preheating tower is much higher than in the case of metal chips. High, and therefore the gap between the metal blocks is very narrow, so that the rate at which the hot flue gas rises through the gap becomes very slow, and it is possible to sufficiently heat the metal block in the preheating tower. At the same time, the exhaust gas itself is completely burned, and the fuel consumption can be greatly reduced. Further, since the metal lump used is a polygonal pyramid or a truncated polygonal pyramid, the metal lump is rapidly melted from thin corners and ridges, and a quick melting operation is realized.

[Brief description of the drawings]

FIG. 1 is a sectional view of a metal melting and holding furnace according to the present invention.

FIG. 2 is a plan sectional view of FIG. 1;

FIG. 3 is an enlarged front view showing a stacked state of a metal lump used in the present invention.

FIG. 4 is a plan view of FIG. 3;

FIG. 5: Conventional metal melting and holding furnace

Claims (2)

[Claims] 1. A method for melting a metal in a metal melting and holding furnace having a preheating tower for preheating a charged metal mass, subsequently melting the preheated metal mass, and supplying the molten metal to a next process. Wherein a polygonal pyramid or truncated pyramid metal lump is packed and laminated in a preheating tower, and the laminated packing body is sequentially melted from the bottom thereof, and hot air is raised through the gap between the metal lumps. Dissolving method of metal characterized by the following. 2. A metal lump used in the metal melting method according to claim 1, wherein the metal lump has a truncated quadrangular pyramid shape.